JP2576369Y2 - Hook storage device for vehicle-mounted cranes - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hook storage device applied to a vehicle-mounted crane such as a truck-mounted crane.

[0002]

2. Description of the Related Art A low pressure relief valve is connected to a pump discharge port of a crane hydraulic circuit or a winding cylinder working oil passage in which the working oil pressure is conventionally restricted by a high pressure relief valve, and during normal cargo handling work, the winding drive of the winding drum is performed. The hydraulic pressure is limited by a high-pressure relief valve, and at the time of overwinding, the high-pressure relief valve is unloaded by a signal generated by an overwinding detection switch. For example, Japanese Patent Laid-Open Publication No. 4-51493 discloses that when the winding cylinder is retracted, the operating pressure of the winding cylinder is at least limited by a low-pressure relief valve which is activated by simultaneous operation of the winding cylinder and the hook storage switch. Is disclosed.

[0003]

In this prior art, in the horizontal position of the telescopic boom storing the hook, that is, in the running posture on the road, the winding between the bobbin and the pulley at the end of the boom is substantially parallel to the boom. When the telescopic boom is moved from the road running posture to the cargo handling posture, the hook storage switch is closed first, and the direction control valve for winding drum control is switched to the lowering side, so that the hook is moved in advance. After the overwind state is eliminated, the boom must be extended or raised. However, when the directional control valve for controlling the bobbin is operated to the lowering side, the directional control valve for controlling the boom telescopic cylinder or the derrick cylinder is erroneously operated. When the boom is extended or raised, the boom is extended or raised,
Because the distance between the winding drum and the pulley at the end of the boom increases,
If the tension of the rope becomes excessive, there is a possibility that the contact engagement portion between the boom tip and the hook may be damaged. This is because the pressure receiving area of the boom telescopic cylinder and the derrick cylinder is set so that the boom can be extended or erected while the load is suspended, and the present invention aims to prevent damage due to this erroneous operation. .

[0004]

According to the present invention, a high-pressure relief valve and an unload valve are connected in parallel between a hydraulic pump discharge port and a tank of a crane hydraulic circuit for operating each part of a crane and other cranes. In a vehicle-mounted crane having a normally open first electromagnetic on-off valve connected between the vent port of the unload valve and the tank, the low pressure is applied to the vent port of the unload valve via the normally open second electromagnetic on-off valve. A relief cylinder is connected between a normally closed contact B and a normally open contact A of a relay which is turned on by a signal generated by an overwinding detection switch. Are connected to the NC contact side of the three microswitches which can be switched to the NO contact side only when they are respectively controlled to the overwinding promoting side, and the first and second contacts are connected to the normally open contact A of the relay. Electromagnetic open An operating solenoid for the valve is connected in parallel, and a hook storing switch is connected between the NO contact of the microswitch and the operating solenoid of the first solenoid on-off valve, which are linked to the control of the hydraulic motor for driving the winding drum. When the storage switch is turned on, there is provided a means for interrupting the power supply to the operating solenoid of the second solenoid on-off valve when the storage switch is turned on.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An on-board crane is, for example, as shown in FIG.
Hydraulically actuated outriggers 1, 1 removably mounted on a truck or other vehicle body frame S;
A post 3 pivotally mounted on a base cylinder of the telescopic telescopic beam 2 of the outriggers on both sides by a pivot hydraulic motor.
A telescopic boom 6 pivotally supported by a foot pin 5 at the upper end of the post 3 so that it can be raised and lowered by a derrick cylinder 4; a boom telescopic cylinder built in the telescopic boom 6; And a winding drum 8 extended from the winding drum 7.
However, the leading end of the cable is fastened to the goose-neck portion so as to suspend and support the hook 11 having two block pulleys 10 sequentially through the plurality of pulleys 9 attached to the goose-neck portion 6a at the end of the telescopic boom. ing. For this reason, hook 11
At the horizontal position of the telescopic boom 6 in which the upper end of the telescopic boom 6 is stored in contact with the gooseneck portion 6a,
Is substantially minimum.

Reference numeral 12 denotes an overwinding detection switch attached to the tip of the telescopic boom 6. At the lower end of the operating cable 13 of the overwinding detection switch 12, a hoisting wire 8a for hanging and supporting the hook 11 is lifted and lowered. The weight 14 freely fitted is suspended and supported. For this reason, while the weight of the weight 14 is acting on the operation cable 13, the switch 12 is closed, but the hook 11 is closed.
When the user lifts the weight 14, the switch 12 opens.

FIG. 1 shows a hydraulic and electric circuit diagram for operating a crane according to an embodiment of the present invention.
Between a directional control valve 16 for controlling the drive hydraulic motor 15 of the directional control valve and a directional control valve 17 for controlling the boom telescopic cylinder
A directional control valve for controlling the derrick cylinder 4, a directional control valve for controlling the swing hydraulic motor, and the like are provided.
Is connected in series to the discharge port as in the prior art. Reference numeral 20 denotes an oil passage from the directional control valve 17 to the boom telescopic cylinder. The operation lever of each directional control valve is rotated in a horizontal plane so that the post 3 can be operated from either the left or right side of the body frame. Each is vertically arranged on both sides.

A high-pressure relief valve 21 and an unloading valve 22 are connected in parallel between the discharge port of the hydraulic pump 19 and the tank T. Open first and second solenoid on-off valves 23,
24 are connected in parallel, and a small-capacity low-pressure relief valve 25 is inserted between the second electromagnetic on-off valve 24 and the tank T. The illustrated first and second solenoid on-off valves are closed because their operating solenoids are in a conductive state, respectively.

An electric circuit for operating the crane is a power take-off device PTO of an automobile engine capable of driving a hydraulic pump 19.
When the switch is switched to the power take-out position, a switch 27 is provided which is closed in conjunction therewith. The switch 27 is connected to the power supply 26 via the switch 27. A relay 28 that conducts and cuts off the coil C is connected, and a rectifier (diode) 29 and 3 are connected between a normally closed contact B and a normally open contact A of the relay 28.
The NC contacts of the microswitches 30, 31, and 32 are connected in series, and the normally open contact A of the relay is connected to an operating circuit 35 of an operating solenoid of the first and second solenoid valves 23 and 24. 36 are connected in parallel.

The micro switch 30 moves the operation lever of the directional control valve for controlling the derrick cylinder 4 to the boom standing position,
That is, it is attached to the direction switching valve so that it can be switched to the NO contact side only when operated to the overwinding assisting side. Therefore, when the operation lever is operated to the neutral position or the boom lowering position, the microswitch 30 returns to the illustrated NC contact side with its own return spring elasticity.

The micro switch 31 is switched to the NO contact side only when the operating lever of the direction switching valve 16 for controlling the hydraulic motor 15 for driving the winding drum is operated to the winding position, that is, to the overwinding assisting side, and the operating lever is set to the neutral position. When the micro switch 31 is operated to the lower position or the lower position, the micro switch 31 similarly returns to the NC contact side.

The micro switch 32 is switched to the NO contact side only when the operation lever of the directional control valve 17 for controlling the boom telescopic cylinder is operated to the boom extension position, that is, the overwinding assisting side, and the operation lever is set to the neutral position or the boom. When operated to the contracted position, the microswitch 32 springs back to the NC contact side.

The NO switch of the micro switch 31 and the first solenoid valve 2
And a hook storage switch (push button switch) 3 disposed on each side of the vehicle-mounted crane between the operation solenoid 3
A rectifier (diode) 3 which connects the solenoids 3 and 33 in parallel and cuts off the power supply to the operating solenoid of the second solenoid valve 24 when the hook storage switch 33 is turned on.
4 is inserted in the operation circuit 35 of the first solenoid on-off valve 23. In the drawing, reference numeral 37 denotes a rectifier 29 connected to the normally closed contact B of the relay 28.
The rectifier 29 prevents the operation of the overwind alarm 37 when the circuit is in the position of FIG. 1.

The present invention has the above-mentioned structure, and in a normal cargo handling state where the hook 11 is located below the weight 14 as shown in FIG. 2, the overwinding detection switch 12 is closed and the power take-out device PTO is provided. When the hydraulic pump 19 drives the hydraulic pump 19 and closes the switch 27, the hydraulic pressure and the electric circuit for operating the crane are in the state shown in FIG. The pump is discharged to the tank T via a bypass 18 such as 16 or 17, and the pump is operated without load. Also, the electromagnetic coil C of the relay 28 conducts through the overwinding detection switch 12, and the relay contact is switched to the normally open contact A, so that the first and second electromagnetic on-off valves 23 and 24 are closed, Accordingly, the unload valve 22 is kept closed, and the operating oil pressure of the crane hydraulic circuit is limited by the high-pressure relief valve 21, so that cargo handling work is possible.

Then, the directional control valve 16 is switched to the upper side to drive the hydraulic motor 15 for driving the winding drum 7 in the hoisting direction (in the direction of the arrow), thereby lifting the hook 11 on which the load is hung, and causing the hook to become a weight. 14 and the overwind detection switch 1
Since the relay 2 is opened to make the relay 28 non-conductive, the relay contact returns to the normally closed contact B with a return spring elasticity, and the overwind alarm 37 is activated. On the other hand, the micro switch 31 is
Is switched to the NO contact side in conjunction with the hoisting control, and the hook storage switch 33 is also open. Therefore, when the relay 28 returns to the normally closed contact B, the first and second electromagnetic switches are opened and closed. The valves 23 and 24 are opened when their operating solenoids are turned off, and the first solenoid on-off valve 23 connects the vent port of the unload valve 22 to the tank T. The drive of the winding drum 7 is stopped by discharging the oil discharged from the pump 19 to the tank, and the winding drum 7 is rotated in the reverse direction by a counterbalance valve (not shown) mounted between the hydraulic oil passages on both sides of the driving hydraulic motor 15. Stopped and stopped.

When the hook 11 is stored from the over-wound state, the direction switching valve 16 is operated upward and the hook storage switch 33 is closed.
The operating solenoid is closed because of conduction, but the rectifier 3
4 shuts off the current flowing from the hook storage switch 33 to the circuits 35 and 36 in order, and returns the second solenoid valve 24 to the open position by spring. Therefore, the set pressure of the low-pressure relief valve 25 is changed to the vent port 22a of the unload valve. Since the unload valve 22 operates as a low-pressure relief valve to drive the winding drum at low pressure, even if the upper end of the hook 11 to be lifted collides with the end of the boom, the unload valve 22 and the unload valve 22 act as a low-pressure relief valve. There is no danger that the contact portion or the like will be damaged, and if the directional control valve 16 is returned to the neutral position, the hook stops at the storage position.

In the hook retracted state in which the upper end of the hook is brought into contact with the boom tip, that is, in the tensioned state of the winding cable 8, the direction switching valve 17 of the boom telescopic cylinder or the delivery cylinder is intended to extend or stand the boom 6.
Is operated to the overwinding assisting side (boom extension or upright side), the microswitch 30 or 32 is switched to the NO contact side, and the operation circuit 3 of the first and second electromagnetic on-off valves is switched.
Unloading 5,36 causes unload valve 22 to open, making it impossible to extend or raise the boom.

Therefore, when the hook is in the stored state,
The distance between the winding drum 7 and the pulley 9 at the end of the boom will increase unless the hook 11 is extended from the winding drum 7 until the hook 11 is lowered below the operating weight 14 of the overwinding detection switch 12. Boom extension or upright operation (overwinding assisting side operation) cannot be performed. Accordingly, when the directional control valve 16 for controlling the bobbin is operated to the lowering side to unwind the winding line 8 from the bobbin 7, the directional control valve 17 of the boom telescopic cylinder or the derrick cylinder is erroneously assisted in overwinding. Even if it is operated to the side, the unload valve 22 is opened and the boom cannot be extended or raised as described above, so that there is no danger that the contact engagement portion between the boom tip and the hook will be damaged.

Although the embodiment in which the rectifiers 29 and 34 for preventing backflow are provided in the electric circuit for crane operation has been described above, instead of providing both rectifiers, a first switch 27 is provided on the switch 27 as shown in FIG. A second relay 38 for operating the overwind alarm 37 connected in parallel with the relay 28 and an operating circuit of the second electromagnetic on-off valve 24 connected in parallel with the hook storage switch 33 to the NO contact of the microswitch 31 A third relay 39 that controls the opening and closing of the second relay 36 may be provided. In FIG. 3, components denoted by the same reference numerals as those in FIG. 1 are corresponding components.

According to the configuration shown in FIG. 3, if the overwinding detection switch 12 is opened during a cargo handling operation and the overwinding detection switch 12 is opened, the second relay 38 is switched to the normally closed contact B side and the overwinding alarm 37 is activated. When the micro switch 31 is switched to the NO contact side by operating the winding cylinder in the over-wound state and the micro switch 31 is switched to the NO contact side, the third relay 39 is turned on and its contact B is opened, so that the hook storing switch 33 is closed. Also, it is clear from the figure that the current flowing backward from the switch 33 to the circuits 35 and 36 is cut off.

[0021]

According to the present invention, in order to move the substantially horizontal telescopic boom storing the hook and minimizing the length of the winding cable to the cargo handling posture, the lowering control of the winding drum is performed so as to eliminate the overwinding state. Even if the boom telescopic cylinder or the derrick cylinder is erroneously controlled to the overwinding assist side, it is possible to prevent breakage of the contact engagement portion between the boom tip and the hook, and furthermore, to operate the hydraulic oil pressure with the high pressure relief valve. In the same manner as before, the automatic stop of the winding drum when the hook becomes overwound during the cargo handling work, and the low hydraulic operation of the winding drum drive hydraulic motor when the hook is suspended and stored for traveling on the road An effect that can be performed is exhibited.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a hydraulic and electric circuit for crane operation.

FIG. 2 is a front view schematically showing the on-vehicle crane.

FIG. 3 is a diagram showing another embodiment of an electric circuit for operating a crane.

[Explanation of symbols]

 Reference Signs List 4 delivery cylinder 6 telescopic boom 7 winding drum 8 winding rope 11 hook 12 overwind detection switch 15 winding drum drive hydraulic motor 19 hydraulic pump 21 high pressure relief valve 22 unload valve 23 first electromagnetic on / off valve 24 second electromagnetic on / off valve 25 low pressure Relief valve 28 Relay 30 Micro switch 31 Micro switch interlocked with winding drum control 32 Micro switch 33 Hook storage switch 34 Rectifier

Claims (1)

(57) [Scope of request for utility model registration] 1. A high pressure relief valve and an unload valve are connected in parallel between a hydraulic pump discharge port and a tank of a crane hydraulic circuit for operating a winding drum and other parts of a crane, respectively. In a vehicle-mounted crane having a normally-open first solenoid on-off valve connected between a port and a tank, a low-pressure relief valve is connected to a vent port of an unload valve via a normally-open second solenoid on-off valve. Normally closed contact B of the relay which is turned on by the signal generated by the winding detection switch
The NC of three microswitches that can be switched to the NO contact side only when the derrick cylinder, the winding drum drive hydraulic motor, and the boom telescopic cylinder are respectively controlled to the overwinding promotion side between the contact and the normally open contact A. The contact side is connected in series, and the operating solenoids of the first and second solenoid on-off valves are connected in parallel to the normally open contact A of the relay, and the micro-motor which is interlocked with the control of the hydraulic motor for driving the winding drum. Switch NO
A hook storage switch is connected between the contact point and the operating solenoid of the first solenoid on-off valve, and means is provided for shutting off the power supply to the operating solenoid of the second solenoid on-off valve when the hook storing switch is turned on. A hook storage device for a vehicle-mounted crane, characterized in that: